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  函数
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  <h1 id="JavaScript中的函数（一些基础知识）"><a href="#JavaScript中的函数（一些基础知识）" class="headerlink" title="JavaScript中的函数（一些基础知识）"></a>JavaScript中的函数（一些基础知识）</h1><a id="more"></a>
<h2 id="关于JS函数"><a href="#关于JS函数" class="headerlink" title="关于JS函数"></a>关于JS函数</h2><p>函数是对象，函数名是指针</p>
<h2 id="函数声明与函数表达式"><a href="#函数声明与函数表达式" class="headerlink" title="函数声明与函数表达式"></a>函数声明与函数表达式</h2><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//函数声明</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">sum</span>(<span class="params">a, b</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">return</span> a + b;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//函数表达式</span></span><br><span class="line"><span class="keyword">var</span> sum = <span class="function"><span class="keyword">function</span>(<span class="params">a, b</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">return</span> a + b</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>两者的区别：在解析过程中，解析器优先解析函数声明，而函数表达式需要当代码执行到它所在的行才会执行</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">sum(<span class="number">1</span>, <span class="number">2</span>)</span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">sum</span>(<span class="params">a, b</span>)</span>&#123;...&#125;</span><br><span class="line"><span class="comment">//正确</span></span><br><span class="line"></span><br><span class="line">sum(<span class="number">1</span>, <span class="number">2</span>)</span><br><span class="line"><span class="keyword">var</span> sum = <span class="function"><span class="keyword">function</span>(<span class="params">a, b</span>)</span>&#123;...&#125;</span><br><span class="line"><span class="comment">//错误</span></span><br></pre></td></tr></table></figure>
<p>注意：尽量不要在块级作用域中使用函数声明，而用函数表达式代替</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">if</span>(p)</span><br><span class="line">	<span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params"></span>)</span>&#123;...&#125;</span><br><span class="line"><span class="keyword">else</span></span><br><span class="line">	<span class="function"><span class="keyword">function</span> <span class="title">b</span>(<span class="params"></span>)</span>&#123;...&#125;</span><br><span class="line"><span class="comment">//不要这样做，而用一下代替</span></span><br><span class="line"><span class="keyword">if</span>(p)</span><br><span class="line">	<span class="keyword">var</span> a = <span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;...&#125;</span><br><span class="line"><span class="keyword">else</span></span><br><span class="line">	<span class="keyword">var</span> b = <span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;...&#125;</span><br></pre></td></tr></table></figure>
<h2 id="函数的内部属性"><a href="#函数的内部属性" class="headerlink" title="函数的内部属性"></a>函数的内部属性</h2><p>在函数的内部，有两个特殊的对象：arguments，this<br>arguments对象有一个<strong> callee </strong>的属性，他是一个指针，指向拥有这个arguments的一个<strong>函数</strong></p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">j</span>(<span class="params">num</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">if</span>(num &lt;= <span class="number">1</span>) <span class="keyword">return</span> num</span><br><span class="line">	<span class="keyword">else</span> <span class="keyword">return</span> j(num - <span class="number">1</span>)</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>这是一个简单的递归，他的缺点是函数内部的递归语句与函数名紧紧地耦合在一起，不利于维护，此时可以利用callee进行修改</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">j</span>(<span class="params">num</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">if</span>(num &lt;= <span class="number">1</span>) <span class="keyword">return</span> num</span><br><span class="line">	<span class="keyword">else</span> <span class="keyword">return</span> <span class="built_in">arguments</span>.callee(num - <span class="number">1</span>)</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>this：引用函数的执行环境对象<br>caller：保存着调用当前函数的函数的引用，如果是全局调用，则该值为null</p>
<h2 id="函数的自带属性"><a href="#函数的自带属性" class="headerlink" title="函数的自带属性"></a>函数的自带属性</h2><p>1、length：函数希望接收的参数个数</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">sum</span>(<span class="params">a, b</span>)</span>&#123;...&#125;</span><br><span class="line">sum.length<span class="comment">//2</span></span><br></pre></td></tr></table></figure>
<p>2、apply,call,bind<br>这三者的用法与区别，移步另一篇博客</p>
<h2 id="关于匿名函数"><a href="#关于匿名函数" class="headerlink" title="关于匿名函数"></a>关于匿名函数</h2><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> say = <span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;...&#125;</span><br></pre></td></tr></table></figure>
<p>这种情况下创建的函数叫做匿名函数，匿名函数的一些使用场景是把它当做值来使用<br>红宝书上的经典例子：</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">createComparisonFunction</span>(<span class="params">propertyName</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">return</span> <span class="function"><span class="keyword">function</span>(<span class="params">obj1, obj2</span>)</span>&#123;</span><br><span class="line">		<span class="keyword">var</span> val1 = obj1[propertyName]</span><br><span class="line">		<span class="keyword">var</span> val2 = obj2[propertyName]</span><br><span class="line">		<span class="comment">//接下来是一些比较规则，自定义</span></span><br><span class="line">		<span class="keyword">if</span>(val1 &lt; val2) <span class="keyword">return</span> <span class="number">-1</span></span><br><span class="line">		<span class="keyword">else</span> <span class="keyword">if</span>(val1 &gt; val2) <span class="keyword">return</span> <span class="number">1</span></span><br><span class="line">		<span class="keyword">else</span> <span class="keyword">return</span> <span class="number">0</span></span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> data = [&#123;<span class="attr">name</span>:<span class="string">'c'</span>, <span class="attr">age</span>: <span class="number">20</span>&#125;, &#123;<span class="attr">name</span>: <span class="string">'a'</span>, <span class="attr">age</span>: <span class="number">30</span>&#125;]</span><br><span class="line">data.sort(createComparisonFunction(<span class="string">'name'</span>))</span><br><span class="line">data[<span class="number">0</span>].name <span class="comment">//a</span></span><br></pre></td></tr></table></figure>
<p>还记得之前所说，sort方法会调用每个对象的toString()方法来进行排序，因此得到的结果往往都不符合预期，而sort可以提供一个函数作为参数，用来定义排序规则。这里就是将createComparisonFunction内部的匿名函数作为值返回之后，再当做参数传递给sort以规定排序的方法。</p>
<h2 id="关于this"><a href="#关于this" class="headerlink" title="关于this"></a>关于this</h2><p>移步另一篇文章，深入理解this对象</p>
<h2 id="模仿块级作用域"><a href="#模仿块级作用域" class="headerlink" title="模仿块级作用域"></a>模仿块级作用域</h2><p>JS中并没有块级作用域的概念，例如</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">count</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">var</span> i = <span class="number">0</span>; i &lt; count; i++)&#123;</span><br><span class="line">		...</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="built_in">console</span>.log(i)</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>不同于大多数其他语言，for循环内部定义的变量i， 并不会随着循环结束而被销毁，闭包的知识可以说明这一点，因为这里的i变量保存在了函数a的活动对象内，因此从函数创建开始，就可以在函数内部任意访问它。<br>而匿名函数则可以模仿块级作用域，修改上述代码</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">count</span>)</span>&#123;</span><br><span class="line">	(<span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;</span><br><span class="line">		<span class="keyword">for</span>(<span class="keyword">var</span> i = <span class="number">0</span>; i &lt; count; i++)&#123;</span><br><span class="line">			...</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;)()</span><br><span class="line">	<span class="built_in">console</span>.log(i)<span class="comment">//报错</span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>这里定义了一个立即执行的匿名函数，因此匿名函数执行完毕之后i就会被销毁，达到块级作用域的效果</p>
<p>作用：这个技巧通常在全局作用域中被用在函数外部，从而避免向全局作用域添加过多的变量与函数，一般来说，<strong>我们都应该尽量少向全局作用域添加变量和函数</strong>。</p>
<h1 id="ES6对函数的扩展"><a href="#ES6对函数的扩展" class="headerlink" title="ES6对函数的扩展"></a>ES6对函数的扩展</h1><h2 id="函数参数默认值"><a href="#函数参数默认值" class="headerlink" title="函数参数默认值"></a>函数参数默认值</h2><p>es5中，并没与提供直接的函数默认参数值的方法，而在es6中，可以这样使用<br><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">x, y = <span class="string">'world'</span></span>)</span>&#123;</span><br><span class="line">	<span class="built_in">console</span>.log(x, y)</span><br><span class="line">&#125;</span><br><span class="line">a(<span class="string">'hello'</span>) <span class="comment">//hello world</span></span><br><span class="line">a(<span class="string">'hello'</span>, <span class="string">'javascript'</span>)<span class="comment">//hello javascript</span></span><br><span class="line">a(<span class="string">'hello'</span>, <span class="string">''</span>)<span class="comment">//hello</span></span><br></pre></td></tr></table></figure><br>参数的变量是默认声明的，所以不能使用let和const再次声明</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">x = <span class="number">5</span></span>)</span>&#123;</span><br><span class="line">	<span class="keyword">let</span> x = <span class="number">1</span><span class="comment">//报错</span></span><br><span class="line">	<span class="keyword">const</span> x = <span class="number">2</span><span class="comment">//报错</span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>使用参数默认值时，函数不能有同名参数</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">x, x, y = <span class="number">1</span></span>)</span>&#123;</span><br><span class="line">	...</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//SyntaxError</span></span><br></pre></td></tr></table></figure>
<p>参数默认值不是传值的，而是每次都要重新计算默认表达式的值，也就是说，参数默认值时<strong>惰性求值</strong></p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">let</span> x = <span class="number">99</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">p = x + <span class="number">1</span></span>)</span>&#123;</span><br><span class="line">	<span class="built_in">console</span>.log(p)</span><br><span class="line">&#125;</span><br><span class="line">a()<span class="comment">//100</span></span><br><span class="line">x = <span class="number">100</span></span><br><span class="line">a()<span class="comment">//101</span></span><br></pre></td></tr></table></figure>
<h2 id="与解构赋值默认值结合使用"><a href="#与解构赋值默认值结合使用" class="headerlink" title="与解构赋值默认值结合使用"></a>与解构赋值默认值结合使用</h2><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">&#123;x, y = <span class="number">5</span>&#125;</span>)</span>&#123;</span><br><span class="line">	<span class="built_in">console</span>.log(x, y)</span><br><span class="line">&#125;</span><br><span class="line">a(&#123;&#125;)<span class="comment">//undefine, 5</span></span><br><span class="line">a(&#123;<span class="attr">x</span>:<span class="number">1</span>&#125;)<span class="comment">//1,5</span></span><br><span class="line">a(&#123;<span class="attr">x</span>:<span class="number">1</span>, <span class="attr">y</span>:<span class="number">2</span>&#125;)<span class="comment">//1, 2</span></span><br><span class="line">a()<span class="comment">//报错</span></span><br></pre></td></tr></table></figure>
<p>上述代码中使用对象的解构赋值设置函数的默认值，只有当函数的参数是一个对象时，变量x和y才会通过解构赋值生成，否则就会报错，以下代码也是这样</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">m, &#123;x = <span class="number">1</span>&#125;</span>)</span>&#123;</span><br><span class="line">	<span class="built_in">console</span>.log(x)</span><br><span class="line">&#125;</span><br><span class="line">a(<span class="number">6</span>,&#123;&#125;)<span class="comment">//1</span></span><br><span class="line">a(<span class="number">6</span>)<span class="comment">//报错</span></span><br></pre></td></tr></table></figure>
<p>也可以通过设置双重默认值来解决这个问题</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">m, &#123;x = <span class="number">1</span>&#125; = &#123;&#125;</span>)</span>&#123;</span><br><span class="line">	<span class="built_in">console</span>.log(x)</span><br><span class="line">&#125;</span><br><span class="line">a(<span class="number">6</span>,&#123;&#125;)<span class="comment">//1</span></span><br><span class="line">a(<span class="number">6</span>)<span class="comment">//1</span></span><br></pre></td></tr></table></figure>
<h2 id="默认参数的位置"><a href="#默认参数的位置" class="headerlink" title="默认参数的位置"></a>默认参数的位置</h2><p>一般情况下，默认参数应该是函数的尾参数，因为在非尾参数设置默认值，实际上这个参数是无法省略的</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">x = <span class="number">1</span>, y</span>)</span>&#123;</span><br><span class="line">	<span class="built_in">console</span>.log(x, y)</span><br><span class="line">&#125;</span><br><span class="line">a()<span class="comment">//1,undefine</span></span><br><span class="line">a(<span class="number">2</span>)<span class="comment">//2, undefine</span></span><br><span class="line">a(,<span class="number">2</span>)<span class="comment">//报错</span></span><br></pre></td></tr></table></figure>
<h2 id="注意此时的length属性"><a href="#注意此时的length属性" class="headerlink" title="注意此时的length属性"></a>注意此时的length属性</h2><p>指定了默认值后，函数的length属性将返回没有默认值的参数个数</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">(<span class="function"><span class="keyword">function</span>(<span class="params">a, b = <span class="number">5</span></span>)</span>&#123;&#125;).length  <span class="comment">//1</span></span><br></pre></td></tr></table></figure>
<h2 id="作用域"><a href="#作用域" class="headerlink" title="作用域"></a>作用域</h2><p>一旦设置了默认值，函数进行声明和初始化时就会形成一个单独的作用域，等到初始化结束，作用域就会消失</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">let</span> x = <span class="number">1</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">a</span>(<span class="params">y = x</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">let</span> x = <span class="number">2</span>;</span><br><span class="line">	<span class="built_in">console</span>.log(y)</span><br><span class="line">&#125;</span><br><span class="line">a()<span class="comment">//1</span></span><br></pre></td></tr></table></figure>
<p>上面的代码中， 函数f调用时，参数y = x形成了一个单独的作用域，在这个作用域内变量x本身并没有定义，所以指向外层的全局变量x，函数调用时，内部的局部变量影响不到默认变量x</p>
<h2 id="rest参数"><a href="#rest参数" class="headerlink" title="rest参数"></a>rest参数</h2><p>es6引入了rest参数，用于获取函数的多余参数</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">add</span>(<span class="params">x, ...y</span>)</span>&#123;</span><br><span class="line">	<span class="keyword">let</span> sum = <span class="number">0</span></span><br><span class="line">	<span class="keyword">for</span>(<span class="keyword">var</span> i <span class="keyword">of</span> y)&#123;</span><br><span class="line">		sum += i</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">return</span> sum</span><br><span class="line">&#125;</span><br><span class="line">add(<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>)<span class="comment">//6</span></span><br></pre></td></tr></table></figure>
<p>注意：rest参数后面不可以再跟其他参数，否则会报错</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">add</span>(<span class="params">x, ...y, z</span>)</span>&#123;</span><br><span class="line">	...</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//报错</span></span><br></pre></td></tr></table></figure>
<h2 id="name属性"><a href="#name属性" class="headerlink" title="name属性"></a>name属性</h2><p>函数的name属性返回函数名，这一属性直到es6才被写入标准<br>需要注意的是，es6对这一属性进行了一些修改，如果将一个匿名函数赋值给变量，es5中name返回空串，而es6返回实际的函数名</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> f = <span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>&#123;&#125;;</span><br><span class="line"><span class="comment">//es5</span></span><br><span class="line">f.name <span class="comment">// ''</span></span><br><span class="line"><span class="comment">//es6</span></span><br><span class="line">f.name <span class="comment">// 'f'</span></span><br></pre></td></tr></table></figure>
<h2 id="箭头函数-amp-amp-尾调用优化"><a href="#箭头函数-amp-amp-尾调用优化" class="headerlink" title="箭头函数 &amp;&amp; 尾调用优化"></a>箭头函数 &amp;&amp; 尾调用优化</h2><p>移步另一篇博客</p>
 
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